I think your best bet is with
www.bavauto.com , they have the rears for $70 and the fronts for $160 it's the best prices iv'e seen and you know that the rears are for the Ti. So the price would be $460 for the bilsteins and you have 220 to get the bav auto springs which are as good if not better than most the german made springs on the market springs. I'm running bilstein sports (from bavauto) and h&r race springs from
www.turnermotorsports.com , but the best mod that i have done to my suspension was getting a stiffer rear sway bar from eibach. I believe that you can get a m-coupe or m-roadster sway bar to fit in the rear and it makes about the same difference.